Java 中的 5 大队列，你知道几个？

import java.util.Date;
import java.util.concurrent.ArrayBlockingQueue;
public class BlockingTest {
    public static void main(String[] args) throws InterruptedException {
        // 创建一个长度为 5 的阻塞队列
        ArrayBlockingQueue q1 = new ArrayBlockingQueue(5);
        
        // 新创建一个线程执行入列
        new Thread(() -> {
            // 循环 10 次
            for (int i = 0; i < 10; i++) {
                try {
                    q1.put(i);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(new Date() + " | ArrayBlockingQueue Size:" + q1.size());
            }
            System.out.println(new Date() + " | For End.");
        }).start();
        // 新创建一个线程执行出列
        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                try {
                    // 休眠 1S
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (!q1.isEmpty()) {
                    try {
                        q1.take(); // 出列
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
}

import java.util.concurrent.LinkedBlockingQueue;
static class LinkedBlockingQueueTest {
    public static void main(String[] args) {
        LinkedBlockingQueue queue = new LinkedBlockingQueue();
        queue.offer("Hello");
        queue.offer("Java");
        queue.offer("中文社群");
        while (!queue.isEmpty()) {
            System.out.println(queue.poll());
        }
    }
}

import java.util.concurrent.LinkedBlockingDeque;
/**
  * 双端队列示例
  */
static class LinkedBlockingDequeTest {
    public static void main(String[] args) {
        // 创建一个双端队列
        LinkedBlockingDeque deque = new LinkedBlockingDeque();
        deque.offer("offer"); // 插入首个元素
        deque.offerFirst("offerFirst"); // 队头插入元素
        deque.offerLast("offerLast"); // 队尾插入元素
        while (!deque.isEmpty()) {
            // 从头遍历打印
            System.out.println(deque.poll());
        }
    }
}

import java.util.PriorityQueue;
public class PriorityQueueTest {
    // 自定义的实体类
    static class Viper {
        private int id; // id
        private String name; // 名称
        private int level; // 等级
        public Viper(int id, String name, int level) {
            this.id = id;
            this.name = name;
            this.level = level;
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getLevel() {
            return level;
        }
        public void setLevel(int level) {
            this.level = level;
        }
    }
    public static void main(String[] args) {
  PriorityQueue queue = new PriorityQueue(10, new Comparator<Viper>() {
            @Override
            public int compare(Viper v1, Viper v2) {
                // 设置优先级规则（倒序，等级越高权限越大）
                return v2.getLevel() - v1.getLevel();
            }
        });
        // 构建实体类
        Viper v1 = new Viper(1, "Java", 1);
        Viper v2 = new Viper(2, "MySQL", 5);
        Viper v3 = new Viper(3, "Redis", 3);
        // 入列
        queue.offer(v1);
        queue.offer(v2);
        queue.offer(v3);
        while (!queue.isEmpty()) {
            // 遍历名称
            Viper item = (Viper) queue.poll();
            System.out.println("Name：" + item.getName() +
                               " Level：" + item.getLevel());
        }
    }
}

import lombok.Getter;
import lombok.Setter;
import java.text.DateFormat;
import java.util.Date;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;
public class CustomDelayQueue {
    // 延迟消息队列
    private static DelayQueue delayQueue = new DelayQueue();
    public static void main(String[] args) throws InterruptedException {
        producer(); // 调用生产者
        consumer(); // 调用消费者
    }
    // 生产者
    public static void producer() {
        // 添加消息
        delayQueue.put(new MyDelay(1000, "消息1"));
        delayQueue.put(new MyDelay(3000, "消息2"));
    }
    // 消费者
    public static void consumer() throws InterruptedException {
        System.out.println("开始执行时间：" +
                DateFormat.getDateTimeInstance().format(new Date()));
        while (!delayQueue.isEmpty()) {
            System.out.println(delayQueue.take());
        }
        System.out.println("结束执行时间：" +
                DateFormat.getDateTimeInstance().format(new Date()));
    }
    static class MyDelay implements Delayed {
        // 延迟截止时间（单位：毫秒）
        long delayTime = System.currentTimeMillis();
        // 借助 lombok 实现
        @Getter
        @Setter
        private String msg;
        /**
         * 初始化
         * @param delayTime 设置延迟执行时间
         * @param msg       执行的消息
         */
        public MyDelay(long delayTime, String msg) {
            this.delayTime = (this.delayTime + delayTime);
            this.msg = msg;
        }
        // 获取剩余时间
        @Override
        public long getDelay(TimeUnit unit) {
            return unit.convert(delayTime - System.currentTimeMillis(), TimeUnit.MILLISECONDS);
        }
        // 队列里元素的排序依据
        @Override
        public int compareTo(Delayed o) {
            if (this.getDelay(TimeUnit.MILLISECONDS) > o.getDelay(TimeUnit.MILLISECONDS)) {
                return 1;
            } else if (this.getDelay(TimeUnit.MILLISECONDS) < o.getDelay(TimeUnit.MILLISECONDS)) {
                return -1;
            } else {
                return 0;
            }
        }
        @Override
        public String toString() {
            return this.msg;
        }
    }
}

import java.util.concurrent.SynchronousQueue;
public class SynchronousQueueTest {
    public static void main(String[] args) {
        SynchronousQueue queue = new SynchronousQueue();
        // 入队
        new Thread(() -> {
            for (int i = 0; i < 3; i++) {
                try {
                    System.out.println(new Date() + "，元素入队");
                    queue.put("Data " + i);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        // 出队
        new Thread(() -> {
            while (true) {
                try {
                    Thread.sleep(1000);
                    System.out.println(new Date() + "，元素出队：" + queue.take());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}